A New Bryozoan of the Genus Dianulites Eichwald from the Ordovician of Gorny Altai and the Russian Arctic
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w Bryozoan of the Genus Dianulites Eichwald from the Ordovician of Gorny Altai and the Russian Arctic A. V. Koromyslovaa, * and N. V. Sennikovb, c, ** a
Borissiak Paleontological Institute, Russian Academy of Sciences, Moscow, 117647 Russia Institute of Petroleum Geology and Geophysics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090 Russia cNovosibirsk State University, Novosibirsk, 630090 Russia *e-mail: [email protected] **e-mail: [email protected]
bTrofimuk
Received April 12, 2019; revised June 3, 2019; accepted June 3, 2019
Abstract—A new bryozoan species Dianulites altaicus sp. nov. (order Esthonioporata) is described from the Sandbian Stage of the Upper Ordovician of the environs of Lake Teletskoe in Gorny Altai. A collection of bryozoans of the genus Dianulites Eichwald, 1829 from the Lower and Middle Ordovician of the Novaya Zemlya archipelago and Vaygach Island in the Russian Arctic has been revised. Bryozoans from the Lower and Middle Ordovician of the Novaya Zemlya archipelago previously classified as D. janischevskyi Modzalevskaya, 1953 were shown to belong to D. altaicus sp. nov. Two groups of species of the genus Dianulites have been identified in the Ordovician of the Russian Arctic: the representatives of the first group had mesozooecia, whereas the representatives of the second group, which includes the new species, did not have mesozooecia, but some of them had minutopores. Keywords: Bryozoa, Esthonioporata, Ordovician, Gorny Altai, Russian Arctic DOI: 10.1134/S0031030120050081
INTRODUCTION The genus Dianulites was established by E. Eichwald (1829); it was assigned by cladistic analysis (Ma et al., 2014) to the order Esthonioporata, superorder Palaeostomata. The species D. detritus Eichwald, 1829, is the type species of the genus (Eichwald, 1859, 1860), although it was later recognized as a junior synonym of the species D. fastigiatus Eichwald, 1829 (Dybowski, 1877; Bassler, 1911; Taylor and Wilson, 1999). The species Dianulites borealis Astrova, 1965 from the Early Ordovician of the Severnaya Zemlya archipelago (Russian Arctic) was assigned to the Tremadocian age and therefore regarded by Ernst et al. (2014) as the oldest representative of this genus. However, according to Nekhorosheva (2015), the age of D. borealis is Floian (Early Ordovician) at the earliest. Astrova (1965) also described D. janischevskyi Modzalevskaya, 1953 and D. preinsuetus Astrova, 1965 from the Early–Middle Ordovician of the Russian Arctic (Novaya Zemlya archipelago, Vaygach Island). The genus Dianulites was the most widespread in the Baltic Paleobasin, where around ten species of this genus existed during different time intervals throughout the Ordovician (Bassler, 1911; Modzalevskaya, 1953; Männil, 1959; Pushkin and Popov, 1999, 2001;
Pushkin, 2002; Koromyslova, 2011). The species D. helenae (Modzalevskaya, 1953) is the oldest in this area and is known since the early Ordovician (Floian, Billingen Regional Stage) (Pushkin and Popov, 2001). D. fastigiatus described from the Floian of t
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